Glyn, a glen or valley through which a river runs.
Gwern, a watery meadow.
Gwydd, a wood.
Gwyn, white, fair.
Gwys, a summons.
Havod, a summer residence.
Is, lower, inferior, nether.
Llan, church, a smooth area, an inclosure.
Llwyn, a grove.
Llyn, a lake, a pool.